问题：

[单选]

Router R1 exists in an Enterprise that uses EIGRP as its routing protocol. The show ip route command output on router R1 lists the following phrase: "Gateway of last resort is 1.1.1.1 to network 2.0.0.0".
Whic h of the following is most likely to have caused this output to occur on R1?（）

A . R1 has been configured with an ip default- network 2.0.0.0 command.
B . R1 has been configured with an ip route 0.0.0.0 0.0.0.0 1.1.1.1 command.
C . R1 has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.
D . Another router has been configured with an ip default - network 2.0.0.0 command.
E . Another router has been configured with an ip route 2.0.0.0 255.0.0.0 1.1.1.1 command.